The FTSEurofirst 300 index ended 0.1 percent lower at 1,383.94 points, having fallen as far as 1,377.49, the lowest level in a week, after data showed the number of Americans filing new claims for unemployment benefits unexpectedly rose last week.

Federal Reserve Meeting

Investors are trying to gauge the strength of the U.S. economy before the Federal Reserve meets next week, looking for clues on the timing of the first U.S. interest rate increase in more than eight years.

"The numbers are slightly disappointing and the market reaction suggests that investors are a little nervous ahead of the Federal Reserve's next meeting," said Keith Bowman, equity analyst at Hargreaves Lansdown.

Confirmation the European Union will impose new sanctions against Russia over the conflict in Ukraine, starting on Friday, and concern about their impact on the European economy, also weighed on stocks.

"There is some fear about a further escalation in the situation in Russia, and that's an uncertainty factor for the European economy," Gerhard Schwarz, head of equity strategy at Baader Bank in Munich, said.

Scottish Independence

Scottish-exposed companies such as Standard Life, SSE and Royal Bank of Scotland rallied after a poll suggested voters in Scotland would reject independence in next week's referendum.

The latest survey by Survation for the Daily Record newspaper showed 53 percent of voters who planned to vote would back retaining Scotland's three-centuries-old union with England. Forty-seven percent intended to vote for independence. The 10 percent of respondents who were undecided were excluded.

RBS rose 1.1 percent. Standard Life and SSE were up 1.5 percent and 2.8 percent respectively.

"The latest poll is relatively reassuring but it's still quite close. Whatever the result of the vote, though, the implication for Europe is that it revives the specter of similar referendums in Spain's Catalonia and Belgium's Flanders," said Alexandre Baradez, chief market analyst at IG France. "It's a risk that investors have to start pricing in."

Clothing retailer Next fell 3 percent, with traders pointing to profit-taking following a strong run after the group's failure to lift its full-year guidance, despite reporting a 19.3 percent rise in first-half profit.